A wide variety of implanted medical devices (IMDs) for delivering a therapy or monitoring a physiologic condition which can employ one or more elongated electrical leads and/or sensors are available. Such IMDs can monitor or deliver therapy to the heart, muscle, nerve, brain, and stomach or other organs.
Examples of such IMDs include implantable cardioverter/defibrillators (ICD), implantable pulse generators (IPG) and pacemaker/cardioverter/defibrillators (PCD) that provide sensing of arrhythmias and programmable staged therapies including pacing regimens and cardioversion energy and defibrillation energy shock regimens in order to terminate a sensed arrhythmia with the most energy efficient and minimally traumatic therapies.
In such IMDs, the integrity of the device is of great importance. The IMDs are desired to be capable of reliable operation and be designed for safety. The implanted IMD are desired to be capable of autonomous operation without active or continuous external monitoring. This is because patients with the IMDs typically resume normal activities of daily life shortly after the implant is performed.
Moreover, the IMDs are desired to consume low power due to the balance needed between device longevity to reduce surgical replacement burden and the miniaturization of the IMDs for comfort and cosmetic reasons. Strict power management constraints are placed on electronics design, and extensive and creative power management and ultra-low power electronic design techniques are desired for the IMDs. This focus precludes the use of many commercially available prognostic sensors, and limits the ability to run computationally expensive firmware algorithms for routine prognostic analysis. As a point of reference, various commercially available prognostic sensors consume more power than the entire power budget of an implantable medical device, where the average power consumption in a modern pacemaker is on the order of tens of microwatts.
Many of the conventional solutions employed in IMDs for fault detection have utilized periodic testing that includes measurements of one or more parameters to determine whether the integrity of the IMD is compromised. One of the challenges associated with the conventional solutions is that the periodic measurements may not always detect with the intermittent nature of the various device conditions that may impact the IMD operation. Additionally, the periodic measurements may not identify device conditions expeditiously for effective containment and to prevent error propagation.
Techniques are needed that will support continuous real-time monitoring and identification of device conditions to prevent error propagation that may lead to adverse performance of an IMD.